Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CHAPTER 18 The Ecology of Organisms and Populations PowerPoint® Lectures for Essential Biology, Third Edition – Neil Campbell, Jane Reece, and Eric Simon Essential Biology with Physiology, Second Edition – Neil Campbell, Jane Reece, and Eric Simon Lectures by Chris C. Romero Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Biology and Society: The Human Population Explosion • Humans – Are by far the most abundant large animals. – Have a disproportionately high impact on the environment. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.1 • The human species – Requires vast amounts of materials and space. – Has devastated the environment for many other species. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings An Overview of Ecology • Ecology – Is the scientific study of the interactions between organisms and their environments. • The environment – Can be divided into two major components. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The abiotic component – Consists of nonliving chemical and physical factors. • The biotic component – Includes the living factors. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Ecology as Scientific Study • Natural history as a “discovery science” remains fundamental to ecology. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.2 A Hierarchy of Interactions • Ecology can be divided into four increasingly comprehensive levels: – Organismal ecology – Population ecology – Community ecology – Ecosystem ecology Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Organismal ecology – Is concerned with evolutionary adaptations that enable individual organisms to meet the challenges posed by their abiotic environments. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.3a • Population ecology – Is concerned with populations, groups of individuals of the same species living in the same area. – Concentrates mainly on factors that affect population density and growth. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.3b • Community ecology – Is concerned with communities, assemblages of populations of different species. – Focuses on how interactions between species affect community structure and organization. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.3c • Ecosystem ecology – Is concerned with ecosystems, which include all the abiotic factors in addition to the community of species in a certain area. – Focuses on energy flow and the cycling of chemicals among the various abiotic and biotic factors. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.3d • The biosphere – Is the global ecosystem. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Ecology and Environmentalism • Our current awareness of the biosphere’s limits stems mainly from the 1960s, a time of growing disillusionment with environmental practices of the past. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The pesticide DDT, which improved agricultural production, – Was developed in the 1950s. – Was determined to have harmful side effects. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Rachel Carson – Was one of the first ecologists to perceive the global dangers of pesticide abuse. – Helped initiate our current environmental awareness with her book Silent Spring. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.4 • The modern environmental movement was catalyzed by Rachel Carson. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.5 • Analyzing environmental issues should be part of every student’s education. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Evolutionary Adaptations of Organisms • The fields of ecology and evolutionary biology are tightly linked. • Evolutionary adaptation through natural selection results from the interaction of organisms with their environments. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Three types of adaptations that enable organisms to adjust to changes in their environments will be analyzed: – Physiological – Anatomical – Behavioral Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Abiotic Factors of the Biosphere • On a global scale, ecologists have recognized striking regional patterns in the distribution of terrestrial and aquatic life. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.6 • Global distribution patterns – Reflect regional differences in climate and other abiotic factors. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Patchiness of the environment on a local scale reveals a mixture of characteristics. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.7 • Habitats – Are specific environments in which organisms live. – Reveal patchiness on an even smaller scale. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Sunlight • Solar energy powers nearly all ecosystems. • Availability of sunlight affects aquatic and terrestrial environments. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Water • Aquatic organisms may face problems with water balance. • For terrestrial organisms, the main water problem is drying out. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Temperature • Environmental temperature – Is an important abiotic factor because of its effect on metabolism. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Some extraordinary adaptations enable some species to live in extreme temperatures. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.8 Wind • Some organisms depend on nutrients blown to them by wind. • Organisms such as plants depend on wind to disperse pollen and seeds. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Wind – Can also affect the pattern of a plant’s growth. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.9 Rocks and Soil • Soil variation contributes to the patchiness we see in terrestrial landscapes. • In streams and rivers, the composition of the soil can affect water chemistry. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Periodic Disturbances • Catastrophic disturbances – Can devastate biological communities. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • After a disturbance, – An area is recolonized by organisms, or repopulated by survivors. – The structure of the community undergoes a succession of changes during the rebound. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.10 Physiological Responses • In mechanisms of temperature regulation, responses by organisms occur quickly. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Acclimation – Is a physiological response that is longer term. • The ability to acclimate – Is related to the range of environmental conditions a species naturally experiences. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Among vertebrates – Birds and mammals can tolerate the greatest temperature extremes because they are endotherms. – Reptiles are more limited in the climates they can tolerate because they are ectotherms. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.11 Anatomical Responses • Many organisms respond to environmental challenge with some type of change in body shape or anatomy. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Behavioral Responses • In contrast to plants, most animals can respond to an unfavorable change in the environment by moving to a new location. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Humans exhibit an especially rich range of behavioral responses. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.12 What Is Population Ecology? • Population ecology – Is the study of how members of a population interact with their environment. – Focuses on factors that influence a population’s size, growth rate, density, and structure. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Population Density • Population density – Is the number of individuals of a species per unit of area or volume. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • How do we measure population density? – In most cases, it is impractical or impossible to count all individuals in a population. – In some cases, population densities are estimated by indirect indicators, such as number of bird nests or rodent burrows. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.13 • Another sampling technique is the mark-recapture method. – Animals are trapped, marked, and then recaptured after a period of time. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.14 Patterns of Dispersion • The dispersion pattern of a population is the way individuals are spaced within the population’s geographic range. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In a clumped pattern of dispersion, individuals aggregate in patches. Flapping Geese (clumped) Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.15a • A uniform pattern of dispersion results from interactions among the individuals of a population. Albatross Courtship (uniform) Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.15b • In a random pattern of dispersion, individuals are spaced in a patternless, unpredictable way. Prokaryotic Flagella (Salmonella typhimurium)(random) Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.15c • Some populations exhibit both clumped and uniform dispersion patterns, but on different scales. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.16 Population Growth Models • Two models, the exponential growth model and the logistic growth model, will help us understand population growth. • The growth rate – Is the change in population size per time interval. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Exponential Growth Model: The Ideal of an Unlimited Environment • The exponential growth model – Describes the rate of expansion of a population under ideal, unregulated conditions. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.17 • A key feature of the exponential growth model is that the rate at which a population grows depends on the number of individuals already in the population. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Logistic Growth Model: The Reality of a Limited Environment • In nature, a population may grow exponentially for a while, but eventually one or more environmental factors will limit its growth. • Population-limiting factors restrict population growth. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • The logistic growth model – Describes growth of an idealized population that is slowed by limiting factors. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.18 • A comparison of the logistic growth model and the exponential growth model Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.19 • Carrying capacity – Is the number of individuals in a population that the environment can just maintain with no net increase or decrease. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Regulation of Population Growth Density-Dependent Factors • The logistic model – Is actually a description of intraspecific competition. – Describes population growth as densitydependent. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Density-dependent factors – Are population-limiting factors whose effects intensify as the population increases in size. – Increase a population’s death rate and decrease the birth rate. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.20 • Natural populations – Do not often show clear-cut cases of densitydependent factors regulating growth. – Can be tested to see if such factors are operating. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • State agencies manage game populations by allowing hunters to reduce the populations. • Game populations may then grow at higher rates. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.21 Density-Independent Factors • Density-independent factors – Are population-limiting factors whose intensity is unrelated to population density. – Include events such as seasonal freezing. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In many natural populations, density-independent factors limit population size before densitydependent factors become important. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.22 • Over the long term, most populations are probably regulated by a mixture of density-independent and density-dependent factors. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Population Cycles • Some populations – Have regular boom-and-bust cycles. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • A case study of population cycles – Boom-and-bust cycles of the snowshoe hare and one of its predators, the lynx Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.23 Human Population Growth The History of Global Population Growth • The human population – Has been growing almost exponentially for centuries. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.24 • Human population growth – Is based on the same parameters that affect other populations: birth rates and death rates. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.25 Age Structure and Population Growth • The age structure of a population is the proportion of individuals in different age groups. • The age structure of a population can help us predict the future growth of populations in different countries. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.26 The Sociology, Economics, and Politics of Population Growth • Age-structure diagrams – Relate to social conditions, such as changes in numbers of working-age people in a population. • Computer models of human population growth – Predict that by about 2080, the human population will peak at about 10.6 billion. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Increases in the human population result in more people consuming resources and dumping pollutants into the biosphere. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.27 • A unique feature of human population growth is that we can control it with voluntary contraception and government-sponsored family planning. • Leaders in almost every country disagree as to how much support should be provided for family planning. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Technology – Has undoubtedly increased Earth’s carrying capacity, but no population can continue to grow indefinitely. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Life Histories and Their Evolution • The life history of an organism – Includes the traits that affect its schedule of reproduction and death. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Life Tables and Survivorship Curves • A life table – Tracks survivorship and mortality in a population. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Table 18.1 • Survivorship curves – Graphically represent some of the data in a life table. – Are classified based on the rate of mortality over the entire life span of an organism. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.28 Life History Traits as Evolutionary Adaptations • Life history traits – Are shaped by adaptive evolution. – Vary with species. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.29 • Two types of life histories are – Opportunistic. – Equilibrial. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In opportunistic life histories, – Individuals reproduce when young. – Individuals produce many offspring. – The population tends to grow exponentially. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • In equilibrial life histories, – Individuals mature later. – Individuals produce fewer offspring, but care for their young. – The population size may be quite stable. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings • Comparison between opportunistic and equilibrial strategies Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Table 18.2 The Process of Science: Does the Environment Shape Guppy Life Histories? • David Reznick and John Endler are scientists who have been investigating the life histories of guppy populations on Trinidad, a Caribbean Island. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.30 • Their hypothesis focused on how predation might cause contrasting life histories in guppy populations by natural selection. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.31 Evolution Connection: Natural Selection on the American Plains • The pronghorn antelope – Is found only in North America. – Exhibits unique adaptations that fit the environment in which it lives. Ducklings Chimp Cracking Nut Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Figure 18.32 • The pronghorn is highly successful in its habitat, – But in a different environment, its adaptations might not be as effective. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings